Why do men have nipples?

Sid_Justice wrote: »

No, you're the expert. You were able to explain and pontificate the scientific proof of evolution based on 'goosebumps and tail bones' I'd like to hear your treatise. Are you not confident your treatise will stand up to scrutiny? Or are you only able to perform in front of soft headed adolescent Jehovah's witnesses?

Coccyx

It is believed that in humans and other tailless primates (e.g. great apes) since Nacholapithecus (a Miocene hominoid),[4][5] the coccyx is the remnant of a vestigial tail, but still not entirely useless;[6] it is an important attachment for various muscles, tendons and ligaments — which makes it necessary for physicians and patients to pay special attention to these attachments when considering surgical removal of the coccyx.[2] Additionally, it is also a part of the weight-bearing tripod structure which act as a support for a sitting person. When a person sits leaning forward, the ischial tuberosities and inferior rami of the ischium take most of the weight, but as the sitting person leans backward, more weight is transferred to the coccyx.[2]

The anterior side of the coccyx serves for the attachment of a group of muscles important for many functions of the pelvic floor (i.e. defecation, continence, etc.): The levator ani muscle, which include coccygeus, iliococcygeus, and pubococcygeus. Through the anococcygeal raphé, the coccyx supports the position of the anus. Attached to the posterior side is gluteus maximus which extend the thigh during ambulation.[2]

Many important ligaments attach to the coccyx: The anterior and posterior sacrococcygeal ligaments are the continuations of the anterior and posterior longitudinal ligaments that stretches along the entire spine.[2] Additionally, the lateral sacrococcygeal ligaments complete the foramina for the last sacral nerve.[7] And, lastly, some fibers of the sacrospinous and sacrotuberous ligaments (arising from the spine of the ischium and the ischial tuberosity respectively) also attach to the coccyx.[2]

An extension of the pia mater, the filum terminale, extends from the apex of the conus, and inserts on the coccyx.
[edit] Structure

The coccyx is usually formed of four rudimentary vertebrae (sometimes five or three). It articulates superiorly with the sacrum. In each of the first three segments may be traced a rudimentary body and articular and transverse processes; the last piece (sometimes the third) is a mere nodule of bone. The transverse processes are most prominent and noticeable on the first coccygeal segment. All the segments are destitute of pedicles, laminae and spinous processes. The first is the largest; it resembles the lowest sacral vertebra, and often exists as a separate piece; the last three diminish in size from above downward.

Most anatomy books wrongly state that the coccyx is normally fused in adults. In fact it has been shown[8][9] that the coccyx may consist of up to five separate bony segments, the most common configuration being two or three segments.
[edit] Surfaces

The anterior surface is slightly concave and marked with three transverse grooves that indicate the junctions of the different segments. It gives attachment to the anterior sacrococcygeal ligament and the Levatores ani and supports part of the rectum.The posterior surface is convex marked by transverse grooves similar to those on the anterior surface, and presents on either side a linear row of tubercles, the rudimentary articular processes of the coccygeal vertebrae. Of these, the superior pair are large, and are called the coccygeal cornua; they project upward, and articulate with the cornua of the sacrum, and on either side complete the foramen for the transmission of the posterior division of the fifth sacral nerve.
[edit] Borders

The lateral borders are thin and exhibit a series of small eminences, which represent the transverse processes of the coccygeal vertebrae. Of these, the first is the largest; it is flattened from before backward, and often ascends to join the lower part of the thin lateral edge of the sacrum, thus completing the foramen for the transmission of the anterior division of the fifth sacral nerve; the others diminish in size from above downward, and are often wanting. The borders of the coccyx are narrow, and give attachment on either side to the sacrotuberous and sacrospinous ligaments, to the coccygeus in front of the ligaments, and to the gluteus maximus behind them.
[edit] Apex

The apex is rounded, and has attached to it the tendon of the Sphincter ani externus. It may be bifid.
[edit] Sacrococcygeal and intercoccygeal joints

The joints are variable and may be: (1) synovial joints; (2) thin discs of fibrocartilage; (3) intermediate between these two; (4) ossified.[10][11]
[edit] Pathology

Injuring the coccyx can give rise to a condition called coccydynia.[12] [13] A number of tumors are known to involve the coccyx; of these, the most common is sacrococcygeal teratoma. Both coccydynia and coccygeal tumors may require surgical removal of the coccyx (coccygectomy). One complication of cocygectomy is a coccygeal hernia.[14] Fortunately, most cases of coccyx pain respond well to nonsurgical treatment, such as medications given by local injection (often done under fluoroscopic guidance).

Goosebumps

Goose bumps, also called goose flesh, goose pimples, chill bumps, chicken skin, funky spots, Dasler Bumps, chicken bumps or the medical term cutis anserina, are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is cold or experiences strong emotions such as fear, nostalgia, pleasure, awe, admiration or sexual arousal.[1]

The reflex of producing goose bumps is known as horripilation, piloerection, or the pilomotor reflex. It occurs in many mammals besides humans; a prominent example is porcupines, which raise their quills when threatened, or sea otters when they encounter sharks or other predators.

Etiology

The "goose bumps" (also "gooseflesh", "goosepimples" or "chicken skin") effect gets its name from geese. Goose feathers grow from stores in the epidermis which resemble human follicles. When a goose's feathers are plucked, its skin has protrusions where the feathers were, and it is these bumps which the human phenomenon resembles. The term "goose bumps" is misleading because the bumps on a goose's skin do not qualify as piloerection, though birds do have the same reflex of extending their feathers out, a function that keeps them warm.

It is not clear why in English the particular fowl goose was chosen, as most other birds have this same anatomical feature. Some authors have applied "goose bumps" to the symptoms of sexually-transmitted diseases.[2] Certainly being "bitten by a Winchester goose" was a common euphemism for syphilis[3] in the 16th century.[4] "Winchester geese" was the nickname for the prostitutes of South London,[5] licenced by the Bishop of Winchester in the area around his London palace.

However, this seductive etymology does not explain why other languages use the same bird as English. "Goose skin" is used in German (Gänsehaut), Italian (pelle d'oca), Russian (гусиная кожа), Polish (gęsia skórka), Czech (husí kůže), Danish (gåsehud) and Hungarian (libabőr). In other languages, however, the "goose" may be replaced by other kinds of poultry. For instance, "hen" is used in Spanish (piel de gallina), Portuguese (pele de galinha), Romanian (piele de găină) and French (chair de poule). "Chicken" is used in Dutch (kippenvel), Chinese (雞皮疙瘩, lit. lumps on chicken skin), Finnish (kananliha), Afrikaans (hoendervleis) and Korean (닭살, daksal). In Hindi/Urdu it is called rongtey khade ho jaana. The equivalent Japanese term, 鳥肌, torihada, translates literally as "bird skin". In Arabic, it is called kash'arirah, in Hebrew it is called simply "duck skin" (עור ברווז).

The same effect is manifested in the root word "horror" in English, which is derived from Latin horrere, which means "to bristle", and "be horrified", because of the accompanying hair reaction.
[edit] Anatomy and biology

Goose bumps are created when tiny muscles at the base of each hair, known as arrectores pilorum, contract and pull the hair erect. The reflex is started by the sympathetic nervous system, which is responsible for many fight-or-flight responses.

As a response to cold: in animals covered with fur or hair, the erect hairs trap air to create a layer of insulation. Goose bumps can also be a response to anger or fear: the erect hairs make the animal appear larger, in order to intimidate enemies. This can be observed in the intimidation displays of chimpanzees,[6] in stressed mice[7] and rats, and in frightened cats. In humans, it can even extend to piloerection as a reaction to hearing nails scratch on a chalkboard, listening to awe-inspiring music,[8] or feeling or remembering strong and positive emotions (e.g., after winning a sports event).[9] Some people have learned to will goose bumps at any time they please.[10]

Piloerection as a response to cold or emotion is vestigial in humans. As we retain only very little body hair, the reflex now provides no known benefit.

In humans, goose bumps are strongest on the forearms, but also occur on the legs, neck, and other areas of the skin that have hair. In some people, they even occur in the face or on the head.

In humans, the areolas of the breasts of females typically show piloerection because of hormonal distribution, for example, when aroused or inside the maternity cycle.[citation needed]

Piloerection is also a classic symptom of some diseases, such as temporal lobe epilepsy, some brain tumors, and autonomic hyperreflexia. Goose bumps can also be caused by withdrawal from opiates such as heroin. A skin condition that mimics goose bumps in appearance is keratosis pilaris.
[edit] Cause
[edit] Extreme temperatures

Goosebumps can be experienced in the presence of cold temperatures. The stimulus of cold surroundings causes the tiny muscles attached to each hair follicle to contract. This contraction causes the hair strands to literally "stand on end." At the same time, the tiny muscles that are contracting are causing a "bunching" of the skin surrounding the hairs, which results in the "bumps" in goosebumps.

In winter, when people get cold outside, they can experience goosebumps. This is the body's way of preserving its own heat by causing the hairs on the skin to stand up, thus reducing heat loss. Goosebumps are often seen in conjunction with shivering in these instances.

Ironically, people also get goosebumps when they are hot, or in the presence of extreme heat. The main reason for this is sweat. As the perspiration accumulates on the skin, it naturally evaporates. As the sweat evaporates, it cools down the skin surface. As this process occurs, a dramatic temperature difference occurs and the body responds to the "chill" of the evaporation of the sweat and the "goosebump response" kicks in.
[edit] Intense Emotion

People often say they feel their "hair standing on end" when they are frightened or in awe. Another intense emotional situation that can cause goosebumps is the "fight or flight" response the body can employ in an extremely stressful situation. As the body prepares itself for either fighting or running, it floods the system with adrenalin, the chemical that speeds up heart rate and metabolism in the presence of extreme stress.[11]

The fight-or-flight response pulls the physiological trigger. When sensing danger, the sympathetic nervous system floods the blood with epinephrine, a hormone that raises the body temperature and primes it for a physical fight. “The sympathetic nervous system also causes a reflex called piloerection, which makes the muscles attached to the base of each hair follicle contract and force the hair up,” says Horatio Wildman, MD, an assistant professor of dermatology at Cornell University. Goose bumps cause the hairs to stand up – just as porcupines raise their quills when threatened. When piloerection occurred in our hairy ancestors, it made them appear larger to enemies and kept them warm. Over the millennia, we lost the fur but not that reflex. Goose bumps do not make hair grow.
[edit] Music

Canadian researchers have suggested that when we are moved by music our brains behave as if reacting to delicious food, psychoactive drugs, or money.

The pleasure experience is driven by the chemical dopamine, which has been linked to addiction. It produces physical effects known as "chills" that cause changes in the skin's electrical conductance, heart rate, breathing and temperature. The responses correlate with the degree to which people rate the "pleasurability" of music.

The new research has shown that dopamine release was greatest when listeners had a strong emotional response to music. "If music-induced emotional states can lead to dopamine release, as our findings indicate, it may begin to explain why musical experiences are so valued,” wrote the scientists.[12]

There you go, I can't believe I typed all that out in 57 seconds.